This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. First we characterized the basic parenting behavior in prairie voles and documented the both mother and fathers coordinate their parenting behaviors to minimize the amount of time that the pups are left unattended on the nest. Furthermore, single mothers do not compensate for the absence of the father by increasing time on the nest or licking and grooming. In a second study we examined the effects of biparental (BP) and single mother (SM) rearing conditions on family dynamics in the next generation and found that SM-reared adult parents exhibited lower rates of pup-directed LG in comparison to BP-reared counterparts. We continued to explore the effect of early life social perturbations by examining the effect of daily maternal separations on later life social behavior. We have explored the reciprocal relationship in oxytocin and CRF system as a possible mechanism regulating the effects of stress on social behaviors, as well as the effects of social loss on the stress axis. This has led to the very exciting discovery that the CRF2 receptor is virtually completely co-localized with oxytocin in the rat and prairie vole hypothalamus. This suggests that CRF2 receptor may play a major role in the regulation of oxytocin secretion. We have continued to characterize the neuroanatomical relationship between the CRF and OT system, which has now been submitted as a manuscript to Psychoneuroendocrinology.